1. Field of the Invention
The present invention relates to a protective cushion for a vehicle occupant""s head and, more particularly, to a cushion which can be inflated along windows of side doors in the event of a side impact or roll-over situation. In detail, it relates to a protective cushion for a vehicle occupant""s head comprising two sheets which are superposed on each other and joined together to form a plurality of chambers arranged in the longitudinal direction of a vehicle.
2. Description of the Related Art
Such a type of a protective cushion for a vehicle occupant""s head is disclosed in International Patent Publication WO96/26087, particularly, FIG. 1 and FIG. 9 of the publication. The known cushion has a vacancy comprising a duct extending from the end at the front side of a vehicle (the front end) to the end at the rear side of the vehicle (the rear end) along the upper edge of the cushion and a plurality of cells (chambers) communicating with the duct and extending downwardly. Between the adjacent cells, a occupant-side sheet (hereinafter, sometimes referred to as xe2x80x9ccabin-side sheetxe2x80x9d) and a vehicle body-side sheet (hereinafter, sometimes referred to as xe2x80x9cdoor-side sheetxe2x80x9d) are connected.
According to the cushion disclosed in WO96/26087, the duct is formed by interweaving the cabin-side sheet and the door-side sheet.
The duct thus formed is not proper for introducing gas into the cells as the goal.
It is an object of the present invention to provide a protective cushion for a vehicle occupant""s head which can introduce gas into chambers formed between sheets timely.
A protective cushion for a vehicle occupant""s head according to the present invention is disposed in the vicinity of a corner between a ceiling and a aide surface of a vehicle cabin so that it is adapted to be inflated with introduced gas downwardly along the side surface. The protective cushion comprises an occupant-side sheet and an body-side sheet which are superposed on each other and joined together so as to form a plurality of vacant chambers between the sheets into which gas is filled wherein the chambers are arranged in the longitudinal direction of the vehicle, and wherein the cushion has a gas passage at an upper portion thereof extending in the longitudinal direction of the vehicle. The protective cushion is characterized in that the gas passage is composed of a cylindrical member provided separately from the sheets wherein the gas passage is provided with at least one opening on the midway thereof.
In the protective cushion for a vehicle occupant""s head, gas supplied to the cylindrical member is supplied into chambers through an end of the cylindrical member and/or openings formed in the cylindrical member. By selecting the length of the cylindrical member and/or the positions of the openings, gas can be introduced into desired chambers from desired positions.
The cylindrical member may be made of a sheet or may be a pipe made of metal or synthetic resin. In case of the cylindrical member being made of a sheet, the sheet composing the cylindrical member (hereinafter, sometimes referred to as xe2x80x9ccylindrical member sheetxe2x80x9d), the cabin-side sheet, and the door-side sheet are sewn together by a yarn. According to the cushion, the sewing is both for forming the cylindrical member and for sewing together the cabin-side sheet and the door-side sheet, thus reducing the man-hour for manufacturing the cushion.
According to the present invention, the upper portion of the cushion, where the cylindrical member sheet, the cabin-side sheet, the door.side sheet are superposed on each other, may be provided with small holes through which bolts or rivets for fixing the cushion to the vehicle body. In this case, the force applied to the cylindrical member is transmitted directly to the vehicle body.
In case of the cylindrical member being made of a sheet, the cylindrical member is connected neither to the cabin-side sheet nor to the door-side sheet.
According to the present invention, the protective cushion further comprises a means or control device disposed in the cylindrical member at a portion downstream from the opening in the gas flowing direction, wherein the means or control device closes or reduces the sectional area of the passage of the cylindrical member until the gas pressure supplied in the cylindrical member reaches a predetermined value, and enlarges the sectional area of the passage of the cylindrical member when the gas pressure in the cylindrical member exceeds the predetermined value. The means or control device may be composed of yarn which can be broken.